1. Field Of The Invention
The present invention relates to electrical connector assemblies and particularly to a user configurable connector assembly including a contact defining a receptacle for freely receiving and holding without bonding an integrated filter component for filtering or suppressing the effects of electromagnetic interference or high frequency and radio frequency interference.
2. The Prior Art
Electromagnetic interference or high frequency and radio frequency signals are often radiated or conducted to susceptible electronic equipment and interfere with the performance of that equipment. Such interference is especially prevalent at connection devices. The effects of electromagnetic interference may vary from mere static on a car radio, to a malfunction of an aircraft navigational system. Electromagnetic or high frequency interference may even result in incorrect readouts on sensitive medical diagnostic equipment. Accordingly, it is extremely important to mitigate or to substantially eliminate the effects of electromagnetic or high frequency interference on a wide variety of instruments. There is an increasing need for electrical connectors that provide good filtering capability over a wide range of conditions and uses and which may be user configurable in order to adapt to a variety of interfaces with other equipment.
With regard to filtered connector assemblies, the prior art is characterized by basically four types. The first type of filtered electrical connector employs a monolithic planar capacitor for engaging each electrical contact axially. Examples of this type of electrical connector would include the following: U.S. Pat. No. 4,376,992, U.S. Pat. No. 4,589,720, U.S. Pat. No. 4,653,838, or U.S. Pat. No. 4,710,710.
A second type of electrical connector is characterized by a series of axial contacts and corresponding apertures for coupling the contacts. Each aperture has a capacitor attached around its circumference. The axial contact is inserted through the capacitor. An improvement of this prior art type employs a tubular sleeve capacitor for receiving electrical contact. Examples of this type of filter would include U.S. Pat. No. 3,710,285, U.S. Pat. No. 3,764,943, U.S. Pat. No. 4,020,430, U.S. Pat. No. 4,215,326, U.S. Pat. No. 4,222,626, U.S. Pat. No. 4,265,506, U.S. Pat. No. 4,296,389, U.S. Pat. No. 4,679,013, or U.S. Pat. No. 4,846,732.
A third type of prior art filtered electrical connector uses a "chip" type capacitor to couple with the contact. Examples of this type would include U.S. Pat. No. 4,500,159, or U.S. Pat. No. 4,804,332, or U.S. Pat. No. 4,880,397.
A fourth type of filtered electrical connector of the prior art utilizes a so called "array" type capacitor which provides a planar filter associated with a series of corresponding axial contacts.
There are significant disadvantages associated with prior art filtering electrical connectors. For example, the "array" filters are expensive and somewhat complicated to manufacture. The "feed through" filters using tubular capacitors suffer from problems of strain and deformation due to vibration and applied compressive forces. Because the contacts must be individually soldered or bonded on a plate, this greatly increases the expense of assembly. The tubular type capacitors also are subject to breakdown due to their fragility and are therefore unsuitable for use in harsh operating environments such as motor vehicles, aircraft, or the like, where components will subject to extremes of temperature and vibration. However, other disadvantages associated with this type of connector are the increased cost and complexity of assembly associated with the need for soldering or otherwise individually bonding all the contacts.
Prior art electrical connectors using chip type filter elements such as capacitors suffer from an inherent inflexibility in that they may be limited to only a few rows of terminal connections. This has the disadvantage of a fixed configuration which cannot be reconfigured in accordance with a customer's design specification due to the fact that the capacitors or other filter elements are installed together in a row, and an entire row of capacitors must be inserted at the same time into a bus bar. See, for example, U.S. Pat. No. 4,804,332.
The prior art has the additional disadvantage that the chip filter components such as capacitors must be permanently placed into the internal portion of the connector before final assembly in order to make the connector functional. Thus, in the prior art, it is not possible to manufacture the connector assembly as a semi-finished product and later insert components to configure the finished product in accordance with a customer's design specifications.
For example, in U.S. Pat. No. 4,500,159 all the chip capacitors are assembled in a row of cavities in a bus bar. Each chip capacitor must be in place in a respective cavity prior to final assembly for the connector to be functional. This completely eliminates the possibility of user configurability in accordance with a customer's unique design specifications. A further disadvantage of this type of prior art filtering connector incorporating rows of capacitors is that due to space considerations, this type of filter may be unsuitable for any kind of high density application.
Another example of a prior art electrical connector is U.S. Pat. No. 4,582,385. In this patent, an integrated electrical circuit component such as a chip capacitor is soldered to a contact. The area of the contact around the chip component lacks a sidewall or any means for freely holding the chip component. Because the chip component must be soldered or permanently affixed to the contact, and in addition has no sidewall protection, every applied torsional force or rotational movement of the contact is transmitted directly through the chip. This renders the chip component extremely susceptible to damage due to improper insertion or even a slight twisting of a contact. Thus, the contact disclosed in U.S. Pat. No. 4,582,385 is believed unsuitable for use in a harsh operating environment where the contact will be subject to extreme vibration such as in a motor vehicle, aircraft, or the like.
In the prior art generally, due to the bonded relation between the chip component and the contact, the direct transmission of torsional forces or rotational movement from the contact to the chip can degrade or destroy entirely the bond and thus the continuity of electrical communication between the electrical component and the contact.
Another important limitation of the prior art is the inability to adapt to a variety of user needs, configurations or operating requirements. For example, in U.S. Pat. No. 4,582,385 all the chip components need to be soldered to a contact and inserted into the body of electrical connector prior to final assembly. This precludes the possibility of a flexible manufacturing system which would enable a connector assembly to be fabricated, stored as a semi-finished product, and then configured in accordance with a customer's design specifications.
Previously, many different filter components would have to be permanently bonded to contacts and either assembled as a finished product or held in storage in order to anticipate the needs of a customer. This resulted in the added expense of keeping large quantities of filter connector components or a great variety of electrical connectors in inventory in order to meet a customer's needs. Also, a customer often was forced to use an electrical filter which merely approximated its needs and thus adversely affected the function and cost of an entire apparatus.
This is a wasteful practice and results in the use of connectors which are not adequately suited to a customer's design specifications for the needs of the system, and accordingly, the connectors do not perform filtering functions as adequately as they should.
The prior art devices have the disadvantage that the manufacturer of the electrical connectors must receive instructions from the customer before the product can be fabricated and assembled. This disadvantageously results in a long lead time with respect to the customer. Any delay in the manufacturing of the connector assemblies can severely upset the predetermined schedule of the customer if the connector assemblies are to be a component of the final product such as a computer.
Another problem in the prior art results when a manufacturer of electrical connectors must fabricate and store large numbers of filter connectors having many types of configurations and differing design requirements in order to meet the anticipated needs of customers. While this can avoid the disadvantage of a long lead time, it nevertheless results in problems in keeping track of a large inventory and may also result in a considerable amount of frozen capital investment.
An additional disadvantage inherent in prior art connector devices is the failure to minimize distances between a filtering means such as a capacitor and the connection between the terminal contact and complete ground. This increases the probability of stray inductances and renders many prior art filter connectors completely unsuitable for use in precision instruments. Prior art devices also suffer from a failure to maximize the area connecting complete ground with the terminal contact and the filtering device.